Introduction: Micro Paintbrush Paint Applicator for Extreme Detail Work

This tutorial explains how to make such a tool and to use it. I will add pictures of the products that I made using this tool, once I've finished some of them.

Problem – solution?

For the first time ever, I needed to make extremely detailed painting, using opaque acrylic miniature paints.

I tested an actual miniature brush, the smallest one I could find, but found it far too large for what I was trying to do: Colorizing engraved letters on the surfaces of push button caps, each letter being less than 5 mm tall. On a scale like that, it’s more like tapping point by point rather than drawing, really. And to achieve perfectly opaque lettering, it would have to be paint instead of markers, yet in order to gain pen-like precision, it would have to be like the tiniest marker you’ve ever seen.

I found myself succeeding at the task by plucking individual bristles out of an unused dish washing brush; they were thin enough but extremely clumsy to handle so I wished there would be a more comfortable and manageable way to do this. Deriving from that, here’s the solution I came up with. It's inexpensive, relatively easy to make, and practically endlessly durable.

Step 1: Things You'll Need

All items were quite effortlessly found from eBay, shipped to me from other continents.

If you don’t take the paint onto account, the most expensive one of the items was the pen, costing 7€. So all in all, a cheaper method than buying a rare specialty artist brush that wears out quickly as they are very sensitive due to the tiny scale.

Exact brand or search term used on eBay is in parenthesis; This is what I used, but you can take these as examples only, if you’d rather use different brands.

  • A mechanical pen that accepts extra thin lead (Rotring Tikky 0.35)
  • Fishing line of the same diameter as the lead that the mechanical pen would use (Balsax Iguana 0.35mm)
  • Tweezers (Label says “PT ESD-15”)
  • Acrylic paint which is flowy and light in composition (Citadel Base, shade titled Ceramite White)
  • Optional: Vinyl cutter machine blades (30° or 45° degree angle blade, blades have red or yellow sleeves, mine are the red ones)
  • Optional: Unless you’ve got amazing vision, a mountable magnifying lens can help a lot. Head-mountable jeweller’s/watchmaker’s goggles are also an option.

Step 2: Micro Paint Applicator Assembly Instructions

Recommended with any and every tutorial you ever use:

First, read the whole instructions from start to finish (including the notes) without doing anything so you understand the whole picture. When you have an idea of the whole picture, get the materials and perform the task as you follow the tutorial step by step. This way you'll avoid any "oops, I didn't realize this would happen" moments that could've been avoided.

Step by step instructions:

  1. Whoever you are, do this under proper task lighting so you can see well. Unless your vision is perfect, put on your glasses or set up a magnifying glass that doesn’t require holding by hand.
  2. You may want to remove the leads from the mechanical pen first.
  3. Cut a strip of fishing line about half the length of the pen.
  4. Hold the pen with its tip pointing upwards. Insert a bit of fishing line into the pen via its tip. It can be a bit tricky to get it started, but for now you only need to get a bit of the end of the line in.
  5. Once you get the end of the fishing line eased in, press the pen against a hard surface (desk) so the button at its other end gets pressed and held in. Because the fishing line is slippery, from here it’s easier to insert it by using tweezers rather than hands. To avoid bending the fishing line sharply, grab it from a quite close vicinity to the pen tip, and gradually insert it into the pen until you can only see the very end of the line sticking out.
  6. At this point the fishing line behaves just like lead: you can hold the button and push the line back in, or press the button to get some line out incrementally. With about 2mm of line sticking out from the end (a bit more than you would leave out if it was lead), dip the line tip in paint, careful not to dip parts of the actual pen. Test draw and see how you like the feel. I found that a slightly scraping motion – like scooping the last remaining ice cream from the bottom of a round ice cream can – works best. I’d say that you can expect to paint in a manner of small dots, and you can make a line about 2mm long at full opacity until the mark starts to taper and fade. This all depends on your paint and the surface that you paint onto, though. You can expect to dip the tool in paint even more often than every 10 seconds because such a tiny amount of paint runs out and/or dries quicker than you’ve ever seen before. There’s just no way getting over having to have patience when doing extremely detailed work!
  7. Optional: If you want to see if the line could hold even a tiny bit more paint in it at a time, with just a tiny bit of the line’s end sticking out, use the vinyl cutter blade to split a bit of the line’s head in half, or even four parts (cut an X). This might give the line an additional vein to store paint into, but because the tiny amounts dry up so quickly, keeping this technique effective requires cutting the used bit of the line off more often and doing the blade splitting job to the fresh end again.

DON’T PUT THE FISHING LINE INTO THE BARREL VIA THE END CAP, it doesn’t work! At first, I tested putting the fishing line into the pen the official way, i.e by removing the end cap and the eraser and dropping the line into the barrel. I found out that no matter how much you keep clicking the button, the fishing line won’t start appearing from the tip. I believe that the mechanism relies on the idea that leads are rigid, but because fishing line bends, the mechanism can’t guide a new one towards the tip. The fishing line is also both too light and too curved to come out of the barrel on its own even if I turn the pen upside down and shake vigorously, so I had to use the slim, tapered tweezers to get them out. I was lucky to have those tweezers.

For some reason, at first I thought that I wouldn’t be able to get the pen to accept the whole piece of fishing line, it seemed to have reached the pen’s locking mechanism that grabbed it satisfyingly, but then it felt stuck, like something was preventing it from going in more. Since the locking mechanism already managed to grab the line, I thought that I wouldn’t have to get it all in but I could just cut away the excess and insert a new short bit every time I needed to replace the line, but then I tried again and with some force and patience, the line got all unstuck and went in with ease. So, don’t give up but be patient, because this is completely possible.

If you use the same or same type of paint as I do, the paint can should be shaken vigorously just before you attempt to use it, and only opened just when you’re about to use it. The container of the paint I use has a kind of gutter shape in the inside of its cap, which I find by far the best spot to dip a paintbrush into: you see what you’re doing, and you don’t need to keep the cap as wide open as you might have to otherwise. Bear in mind that this paint dries extremely quickly, and the thinner the layer of paint, the quicker it will dry. The point of a paintbrush is to store some paint into it so there’s flow. Realize that because this is not a hairy brush, and it’s absolutely tiny, it won’t be able to store much paint in it at a time. If you need to fill larger areas, I recommend making those first, with a brush that allows some flow, and using this technique only to finish off edges or to make extreme details that you could never otherwise achieve.